Cut-out



` Feb. 22, 1938. A. RAMsEY 2,108,993

CUTV-OUT Filed June 9, 1934 4 Sheets-Sheet l l@ f6' /2 /6- ?QLQZ /a ,2f 3*? /o g f6 22 "Z3 Jaw/@0n Feb. 22, 1938.

A. RAMsr-:Y 2,108,993

CUT-OUT Filed June 9, 1954' 4 Sheets-Sheet 2 Feb. 22, 1938. A. RAMsEY 2,108,993

CUT-OUT Filed June 9, 1934 4 Sheets-Sheet 5 Patented Feb. 22, 1938 PATENT OFFICE amasse- CUT-our Allan Ramsey, Evanston, Ill., assignor to Schweitzer & Conrad, Inc., Chicago, Ill., a corporation of Delaware Application June 9, 1934, Serial No. 730,075 49 clam (ci. zool-114) My'invention relates circuits.

More particularly, my invention relates to an improved cutout for the primary circuits of an electrical distribution system. Primary circuits usually extendv from electrical substations, or transformerA stations on a high potential line, out over\the immediate vicinity, and supply current to the service transformers for light and power distribution. Such circuits commonly carry potentials in the neighborhood of '7,500 volts, the voltage being sometimes less than this and sometimes slightly higher.

Itis common practice to install primary cutouts in the primary leads of the distribution transformer. The function of the cutout is automatically to disconnect from and isolate from the feeder circuit a transformer which breaks down or is otherwise either partially or completely short-circuited.l By thus isolating a defective transformer or a defective section of the circuit, outage of the entire feeder with its any transformer stations is prevented. That is, if. the cutout were not there to disconnect the 'faulty transformer, the oil circuit breaker at the substation end of the feeder would be tripped out, thereby disconnectingv service from a large number of customers.

A form of automatic disconnecting or circuit interrupting means used extensively in these circuits is the ordinary type of plug and socket cutout, wherein the plug carries a. fusible link adapted to have connection with terminals in the socket, which terminals are connected in the line.

As ordinarily constructed, the plug of this type of cutout is held in the socket by frictional contact of the contact terminals on the plug with the contact terminals in the socket. The contact terminals in the socket are commonly slotted at numerous points to afford a greater resiliency of contact with the contact terminals or ferrules on the plug member of the device.v 'I'he holding of the plug in the socket by frictional contact,

, in this manner does not afford the desired se- 45 curity against blowing out or loosening of the v plug by the reaction to the explosive force upon 'blowing of the fuse by short-circuit or overload and, as a result, the-plug mayI be blown out of the socket or loosened to the extent that it may be jarred or otherwise displaced from its position in the socket. I

Where'frictional contact is relied upon to hold the plug in place and the contacts in proper lengagement, there has been adenite obstacle to to cutouts for electrical rm and positive locking of the plugin the socket and the contact terminals on the plug in. proper contact with the contact terminals in the socket, namely, the frictional resistance to blowlng out or loosening of the plug upon overload or blowing of the fuse could not be sufllcient to 5 prevent the man reloading the fuse from pulling the plug freely out of the socket. With this limitation, the matter of holding the plug in place under the explosive force which accompanies blowing of the fuse has presented a difficult practical problem.

Bayonet locks which require turning of the plug after it is inserted or pushed into the socket complicate manipulation and present parts which are subject to corrosion and possible freezing in a manner which might make it difficult to remove the plug. And they present a lock which is in lock it in place or presenting locking parts which are operative under normal conditions when there is no blowing of the fuse, or subject to corroslon or possible freezing. o

According to my invention, I providea lookin devicewhich is normallyl in released position with the plug in place in the socket, and is operable only at the instant required. This is attained in the illustrated embodiment'of the invention by 35 making the locking device operable by the pressure generated or the explosive force which occurs upon blowing of the fuse. And provision is made for releasing the lock when the explosive force is relieved. Other manners of ren- 40 dering the locking device operative at the instant required are" however, contemplated within the scope of the broader aspects of the present in-v vention. The rendering operative of the locking device only at the instant required with the plug normally released enables free and quick withdrawal and insertion of the plug at all times. Another object is to provide anfimproved arc chute arrangement for directing the gases and metal vapors out through the open bottom of the socket and away from the porcelain or other insulating body of the socket to protect the same from damage by the arc upon blowing of the fuse.

; -Another object is to provide an improved conthe lay of the strands of the conductor.

tact clip construction and assembly, and an improved manner of securing the clip to the base or terminal block of the contact clip assembly. The particular clip assembly herein illustrated includes a contact clip slotted at numerous points to afford a greater resiliency of contact with the ferrules on the fuse tube and embraced by a tensioning spring which urges the contact ngers toward each other.

Another object is to provide an improved retened-side fuse spring for withstanding high Y pressures without distortion.

Another object is to'provide a spring and cable assembly in which a stranded conductor is Wound into a helix in a direction counter to the lay of the strands of the conductor, and placed within a spring wound into a helix in the direction of 'I'his combination prevents the strands of the cable or the turns of the cable helix from paralleling the turns of the spring, thereby greatly reducing the tendency for the cable to be pinched between the turns of the spring, which spring collapses to establish the desired gap upon blowing of the fuse.

` The fuse link assembly which l1A employ is of' the type described and claimed in my oopending application Serial No. 671,660, ledMay 18, 1933, with certain improvements to make it universal or adapt it for use with the fuse device constituting a part of the plug of the cutout of the present invention, and with the dropout type ejector cutout box of my copending application Serial No. 734,262, filed July 9, 1934.

This fuse link assembly also embodies an improved visual indicator feature and other improvemen'ts which will hereinafter appear.

Another object is to provide an improved combination of an insulating outer sleeve having metallic ferrules constituting outer terminals, a pair of inner terminals within and adjacent one end of the outer sleeve and connected electricallywith the outer terminals, one of the inner terminals being movable toward. the other end of the sleeve, with a fusible element between the inner terminals and an inner sleeve of insulating material closely surrounding the inner terminals and'closed by and attached to the movable inner terminal to move therewith toward the other end of the outer sleeve when the fusible element fuses.

Another object is to provide a silver fusible element in the present combination withI the outer insulating sleeve and the inner insulating sleeve closely surrounding the inner fuse terminals and closed by' and attached to the movable inner terminal to-move therewith toward the other end of the outer sleeve when the fusible element fuses, whereby the silver fusible element is excluded from too free access to atmosphere. My invention further provides an improved mounting bracket vwhich permits mounting the cutout at the side of or under the cross-arm, and provides a tight clamping of the swivel joint by placing the tongue of the cutout clamp between the split ends of the cross-arm bracket.

Further features and advantages and a concrete understanding of the present invention will be more apparent from the following detailed description taken in connection with the accompanying drawings, in which:

Figure 1 is a view illustrating my improved form of cutout mounted upon a cross-arm;

Figure 2 is a view similar to Figure 1, showing the cutout mounted in another positionby means of the bracket constituting a part of the present invention;

Figure 3 is a fragmentary sectional view showing the upper end of the socket member and the plug member in operative association with the handle of the plug member and a portion of the fuse device lin elevation;

Figure 4 is a fragmentary sectional view showing the lower end of the socket member with the lower end of the fuse carried by the plug member in operative association therewith;`

Figure 5 is a transverse sectionalview taken on the line 5-5 of Figure 4;

Figure 6 is an end view looking into the lower end ofthe socket member of the cutout, and

'showing the lower end of the fuse member of the plug part in operative association therein;

vfuse ure 12 is to be laid below Figure 11 with the dot v and dash line a/-a of Figure 12 on the dot and dash line a-a of Figure 11).

Figure 13 is a fragmentary detail section on an enlarged scale and showing the locking device for locking the plug member of the cutout within the socket member; and

Figure 14 is a fragmentary elevational view of the upper end of the fuse link assembly showthe plug member 4 is adapted for insertion in the top of the socketmember 2, this arrangement bearing particular relation to the type of, fuse employed; as will hereinafter appear.

The socket member 2 principally consists ofr a tubular member of wet process porcelain, or other suitable insulation, finished with a chocolate glaze inside and out, and formed externally and intermediate its ends with two longitudinal spaced annular shoulders 5 5, between which engage a split clamp 6. The clamp 6 is gripped tightly about the body of the socket 2,by a pair of bolts l extending through the sides of the clamp and engaged in suitable nuts. of one side or" the clamp ii is extended and bent laterally to form a mounting tongue which @ne end is secured, for example, to the cross-arm III of a transformer pole or other point of disconnecf tion by a bracketA II. The holes through the clamp part having the extending tongue 8 for the lthe bottom of the cross-arm. These parts I2 and I5 have outwardly directed anges I6 at their opposite ends. The parts I3 and I4 are inter changeable. In Figure 2, the part` I4, which is of L-shaped form, is fitted against the bottom of the 'cross-arm with its flange I6 in spaced relationto the flange on the adjacent end of the part I5 and its free end extending out from the opposite side of the cross-arm, and the part I3 is applied with its base against the .side of the cross-arm between the flange I6 on the part I2 and the extending end of the clamp part I4, and with one of its flanges I6 in spaced relation to the flange I6 on the adjacent end of the clamp part I2 and its other flange I6 adjacent the extending end of the part I4. The tongue 8 of the clamp 6 is swiveled between the extending end of the clamp part I4 and the flange on the adjacent end of th clamp part I3 upon a carriage bolt II which may be loosened to-permit the cutout to be adjusted or swung to any angular position about the axis of the bo1tI1, and tightened-\ to clamp the cutout firmly in the position in which it is arranged. Carriage boltsl I8 pass through the other pairs of spaced flanges I6 for gripping the bracket tightly in place about the cross-arm If The arrangement of Figure 2 affords a generally horizontal mounting of the cutout under the cross-arm I0.

I Where it is desired-to mount the device on the side of the cross-arm, as shown i'n Figure l, the clamp parts I3 and I4 are interchanged. This directs the extending end of the part I4 downwardly from the bottom of the cross-arm instead of outwardly from one side, as before, and disposes the axis of the bolt I1, forming the swivel connection between the tongue 8 and the bracket II, horizontally insteadof vertically, as before, and the cutout on one side of the cross-arm. By

reversing the application of the bracket II, the` cutout may, of course, be disposed at the opposite k side ofthe cross-arm in either case, the swivel connection at I'I, .in each case, permitting adjustment for mounting or arrangement of the cutout at any desired angle.

` Referring to the detailed construction of the socket member 2 as shown in Figures 3 and 4, it will be noted that this member is in the form of a hollow sleeve 20, headed at its upper and lower ends `at 2I and 22 respectively, and is formed externally with petticoats -23 between the upper headed end 2l and the upper shoulder 5 and between the lower shoulder 5 and the lower headed end 22. This socket member 2 is preferably constructed of wet process porcelain, as already explained, although other suitable insulating materials may be employed within the scope of my present invention. I Contact terminal assemblies 26 and 2'I are provided inthe enlarged bores 24 at the upper and lower ends of the central bore 25, and the upper and lower ends of the central bore 25 are enlarged at 28 for a purpose whichl will hereinafter appear.

'I'he upper and lower contact terminal assemblies 26 and 21 each comprises a clip base, preferably constructed of cast hard bronze or other suitable conducting material. The clip bases 29 at the upper and lower ends are substantially alike. Each has a hub `or sleeve portion 30 provided integrally at one side with a thickened lug 3l having a transverse aperture 32 for receiving the bared end of the line wire 3 from either side, and each clip base has a pair of screws 33 for binding the inserted ends of the line wires 3 securely in place. The side wall of the headed upper end 2I of the sleeve 20 has an opening 34 for leading the upper line conductor 3 into one side of the upper clip base,

vand the side wall of the headed lower end 22 of the sleeve 20 has openings 34 at opposite sides for leading the lower line conductor 3 into either side of the lower clip base 29. The lower end of the upper clip base and the upper end of the lower clip base are provided integrally with base flanges 35 extending annularly between the opposite ends of the lugs 3 I. The bases 29 seat upon the radial shoulders 36 between the bores 24 and 28 at the upper and lower ends of the socket, and

gaskets 38, preferably of relatively soft composition cork or other suitable material are interposed between the shoulders 36 and the clip base-s 29. These bases 29 are secured in place by a cement or alloy binder or filler 39 lled in around the bases 29 which are centered in the bores 24 and over the flanges 35 in the illustrated embodiment up to the upper and lower ends of the hub or sleeveportions 30 and adhering to the inner surfaces of the bores 24 and to the bases 29 to secure the same rmly in place.

The bore or hollow interior through each clip base 29 has an annular groove 4U, the sides of which, preferably,l are tapered as shown at 4I, and the upper end of the bore through the upper base and the lower end of the bore through the lower base preferably are tapered outwardly slightly at 42. The lower end.of the upper base and the upper end of the lower base are counterbored slightly at 43 to permit the desired resiliency of the upper and lower contact clipsv 44 and 45.

The upper contact clip 44 is preferably constructed of relatively soft copper tubing or other suitable material. In assembling the upper clip and base', the tubular clip 44 is inserted into the bore through the clip base 29 into the position shown, and the clip 44 is then rolled or spun at 45 out into the annular groove to secure the clip in place in the base 29. This rolling or spinning is preferably accomplished without changing the outside diameter of the clip and the opposite sides of the external bead thus formed are tapered in conformity with the taper of the sides of the groove 4I! and fit snugly thereagainst. l The upper end of the clip 44 is preferably rolled or spun out against the tapered end of the bore through the upper clip base 29. The rolling or spinning of the clip 44 at 46, in addition to forming an external bead and securing the clip in place in the base 29, forms an internal groove 48 `for cooperation with the locking device for the plug, as will hereinafter appear.

The clip 44 is slotted upwardly from its lower end at numerous points, 4as indicated at 50, to

vform spring contact fingers and afford a greater resilience lof contact with ythe fferrules on the fuse member of the plug 4. The lower ends of the spring contact fingers are deformed inwardly slightly, leaving an annular depression externally about the contact fingers, and these fingers are embraced by a garter spring 52 lying in the annular depression thus formed. The spring 52 is coiled left-hand, in the illustrated embodi ment of the invention, with maximum initial tension, and may be heat-treated after forming the hooks 53 at the opposite ends of the same (Flgure 9). When the spring 52 is applied and the hooks 53 engaged as shown, the spring urges the contact fingers of the clip toward each other. The spring 52 is preferably light and soft acting so as not to produce too much friction on the ferrule. The spring 52 lies in the groove 54 in areenforcing ring 55 which may be formed of brass rod or other suitable material, and which prevents deforming the contact fingers of the clip beyond their elastic limit. This is important because if the contact fingers are deformed beyond their elastic limit, a permanent set is produced which cannot be overcome by the garter spring 52. The enlargement 28, at the upper end of the bore 25, provides adequate accommodation for the garter spring and reenforcing ring assembly around the contact fingers of the clip 44.

The lower contact clip 45 is likewise preferably constructed of relatively soft copper tubing or other-,suitable material. 'This clip and its base 29 are assembled in the manner of assembling the upper clip and base, namely, the tubular clip 45 is inserted into the bore through the lower clip base 29 into the position shown, and the clip is then rolled or spun at 46' out into the annular groove 40 to secure the clip '45 in place in the base 29. As with the upper clip,

this rolling or spinning is preferably accom-l 'plished without changing the outside diameter of the clip 45, and the yopposite sides of the external bead thus formed are tapered in conformity with the `taper of the sides of [the groove 48 and fit snugly thereagainst. The lower end of the clip 45 extends downwardly from the bottom of the base 29 and is spun or rolled outwardly to trumpet or flaring shape as illustrated at 58. This trumpet or'flaring end 58 of the clip 45 forms an arc-chute arrangement for directing the gases and metal vapors out through the open bottom of the socket and away from the porcelain or other insulating body ofl the socket to protect the same from damage bythe arc .upon blowing of the fuse. y

The clip 45 isA slotted downwardly from its upper end at numerous points as indicated at 59 in the manner of the slotting of the'lower end of the clip 44 to form spring contact fingers and afford a greater resiliency of contact with the ferrule on the lower end' of the fuse member of the plug 4. The uppenends of the spring contact ngers thus formed are deformedA inwardly, leaving an annular depression similar to ,fingers of the clip beyond their elastic limit in the manner described in connection with the corresponding spring andring for the upper clip. The enlargement at 28 of the lower end of the bore 25 accommodates the lower clip fingers and the surrounding spring and reenforcing ring.

Referring now to the detailed construction of the plug member 4, the handle 60, which is preferably constructed of wet process porcelain, chocolate glazed, or other suitable insulating material, is formed with a depending hood 6I which is adapted 4to t down over the upper end of the )socket 2, thereby excluding moisture and shielding the operators hand from any possible injury in pulling or inserting the plug. An insert 62, preferably formed of cast hard bronze or other suitable material, has at its upper end a ribbed post cemented firmly in place in an opening 63 in the handle by a suitable cement or alloy binder indicated at 64. The lower endof the insert 62 is enlarged slightly .and internally'threaded or tapped for receiving the externally threaded upper end 65 of the upper ferrule 14 for the fuse tube 10.

The fuse which I employ in my improved cutout is of the type described and claimed in my copending application Serial No. 671,660, filed May 18, 1933, and embodies a number of improvements in this type of fuse, as will hereinafter appear. 'I'his fuse clears minor or low current faults as positively as it clears more severe faults, as during a short circuit or heavy overload; its

operation does not require explosive action, but

in all cases the instantaneous collapse of the coil spring establishes a definite and sufficient gap regardless of the amount of fault current. the same time short circuit and heavy overload faults are cleared without attendant danger that excessive pressure may cause destruction of the equipment. Heavy pressures occur within a small cylinder or chamber which is a part of the fuse link, and the tube proper is freely vented. Preheating or corrosion ,does not deteriorate and result in causeless operation of the fuse element, because this element is made of a pure metal which has proved to be vastly superior from the standpoint of its resistance to corrosion and its ability to operate at a higher percentage of its melting point without deterioration. It is not necessary to replace unblown fuse vlinks after an over-current has blown other fuses in the same circuit, and a permanent and exceptional accuracy of fuse ratings is obtained. The time delay characteristic and short arcing time make the fuse exceptionally suitable for selective operation.

Referring particularly to Figures 10, 11, l2 and 13, the fuse is enclosed in a tube designated 'l0 in its entirety which is preferably formed of grade X rolled Bakelite or phenol condensation product tubing 'll rolled on a fiber liner 12, or other suitableinsulating material. At its upper end the outer diameter of the tube 'll is reduced at 13 to receive the upper ferrule 14 which is preferably formed of brass rod or other suitable material. At its lower end, the outer diameter of the tube 'Il is reduced at 15 to receive the lower ferrule 16 which is preferably formed of cast hard bronze or other suitable material. The extreme ends of the tube 'll are preferably chamfered slightly, as illustrated. The upper reduced end of the tube ll is provided with an external groove l1, and the inner surface of` the ferrule 'i4 is provided with a downwardly flaring or generally conical groove i8 which, when the ferrule is in place upon the reduced upper end of the tube with its lower end in engagement n with the shoulder i9, registers withthe groove TI. li conical spring snap ring 80, formed of seamless brass tubing (half hard) and split at 8|, engages the shoulder at the upper, end of the groove 11 and the shoulder at the lower end of the groove 18, and anchors or secures the ferrule 14 firmly to the tube without screws or the like and at low cost, and ina small space. At the same time, an exceptionally strong joint is provided between the'tube and ferrule. In assembling these parts, the snap ring 80 may be applied to the'groove 11v before placing the ferrule upon the tube. Then as the ferrule is passed down over the upper end of the tube, the larger lower end of the snap ring may be pressed into the groove 11 to permit passage of the ferrule into place, whereupon the ring 80 will spring out into the conical groove 18 and, by its engagement with the shoulder at the lower end of this groove, will anchor the ferxule firmly in place upon the tube. l

The lower reduced end 15 of the tube 1| is provided with a groove 82 similar to the groove 11, and the inner surface of the ferrule 16 is provided with an upwardly iiaring or generally conical groove 83 corresponding with the groove 18. A-spring snap ring 84 slit at 85, similar to the ring 80, and engaging in the grooves 82 and 83 in a similar manner, locks or secures the lower ferrule 16 firmly in place upon the lower reduced end of the tube 1|. This ring 84 and the ferrule 16 may be applied in the manner described in connection with the ring 80 and the ferrule 14, and the upper end of the ferrule 15 engages the annular shoulder 86 at the upper end of the lower reduced portion 15.

The upper cable terminal and spring fastener 90, which is preferably formed of brass rod or other suitable material, is flanged or headed to form a button 9| which seats upon the upper end of the ferrule 14. 'I'he reduced portion 92, depending integrally from the button 9|, has a helical groove into -which the upper few turns of the coiled fuse spring 93 are threaded, and an integral depending socket 94 receives the upper end of the stranded cable 95 and is pressed securely thereon. The stranded cable 95, which is preferably of stranded copper, or other suitable material, is connected to the lower cable terminal and spring fastener 96 by rigidly securing it in the socketed part 91 thereof, as by inserting it in the socket and pressing or fiattening the socket firmly thereon and into secure engagement therewith. The terminal and fastener 96has a helical groove for threaded engagement with the lower few turns of the spring S3. The terminal 96 is knurled externally at 98 and is tapped or threaded internally at 99 for receiving the threaded upper end of the upper fuse terminal which is formed of copper or other suitable or preferred material.

The lo'werfuse terminal |0| is formed of similar material, and this terminal and the terminal |00 are connected by a strain wire or tensile element |02 arranged to bear the mechanical stress. The upper end of the wire |02 is inserted in a socket cr opening in the lower end of the ,terminal |00, and is secured rigidly in place as by punching at |04l the stock of the terminal |00 into firm binding engagement with the wire, orv

' gagement with the wire, or, asl before, by flattening the socket upon the wire.

The fusewire ||0 preferably is of silver, and the strain wire |02 preferabhr is of nickel chromium wire. The upper end of the fuse wire ||0 is inserted in an opening in the terminal |00 and is secured firmly in place therein as by punching the adjacent side of the terminal into firm engagement therewith,for flattening the same thereon. The lower end of the wire ||0 is inserted in an opening in the terminal |0 and may be secured firmly in place therein as by punching the adjacent sides of the terminal I0| into firm engagement therewith, or flattening the same thereon. Intermediate its ends, the fuse wire ||0 is coiled about the strain wire |02.

It has been found that silver, as used in devices of this sort, has unusual characteristics. First there is not an appreciable absorption of oxygen until temperatures close to the melting point are reached, and this oxygen is'released again upon a slight drop in temperature. Even if there is some oxidation, the oxide has conducting prop-4 erties similar to those of silver. Also, it has been found that under certain circumstances, silver will form undesirable compounds with other elements on blowing. In -some of the experiments and tests made on fuses under various condi- .tions, the blowing of the fuse appeared to be more violent than the power current would seem to account for.

This applicant, by a combination of the silver fusible element with the outer insulating sleeve and the inner insulating sleeve closely surrounding the inner fuse terminals and closed by and attached to the movable inner terminal to move therewith toward the other end of the outer sleeve when the fusible element fuses, all as will hereinafter appear, excludes the silver fusible appears to be conductive, and that the timecurrent characteristic, which is an all-important factor under certain circumstances, can readily bemaintained over long periods, is utilized.

The fusewire ||0 of silver'or other fusible conducting material, preferably whose oxide is a conductor, and the comparatively high resistance strain wire |02, both are completely enclosed and shielded from atmosphere, gases and moisture, by a tube ||2 formed of fiber or other insulating material. The upper end of the tube |2 closely surrounds the upper fuse terminal |00 beneath the integral flange ||4 thereon, and is shrunk or crimped at I5 into the annular groove I6 to close the upper end of the tube I2 against access of atmosphere to the silver fusible element and tosecure the tube I|2 to the upper fuse terminal |00 so that it will-move therewith toward the other end of the outer sleeve when'the fusible element fuses. The lower end of the tube ||2 passes freely over and closely surrounds the lower fuse terminal |0| and extends down toa position ben'eath this terminal and from the lower end of the fuse tube, as illustrated in Figure 12. The tube ||2 offers no impairment to free sep- `aration of the terminals |00 and |0| upon blowing of the fuse, yet, at the same time, it is rigid throughout its length and by its engagement at the upper end with the terminal |00 and its cooperation with the terminal |0l holds the terminals and I0| rigidly against relative lateral movement, such as otherwise might result in movement or even crimping or twisting of th fuse wire H0 and/or strain wire |02.

For the purpose of setting the fuse and holding the same set, the lower end of the terminal |0I is provided with an extension H5 formed of stranded conducting cable or other suitable material. Several strands of copper cable, preferably tinned, or depth cable are employed in the illustrated embodiment, although this may, of course, vary widely. The upper end of this cable is inserted in a socket H8 on the lower end of the terminal I0 I, and this socket is flattened into rm engagement with the cable to secure the same therein. Within its length, the stranded cable I|5 is provided withla conical bushing |20 securely anchored in position upon the cable |I5 as by flattening the upper end of the bushing into firm engagement with the cable at I2 l. The lower conical part of the bushing |20 is engageable with a clip |22 to hold the fuse in set posi tion. The clip |22 is formed by the outstanding and slightly hooked sides |23 of a conical socket |24 in the lower end of a tongue |25 formed integral with the lower ferrule 16 and depending therefrom, the integral sides |23 rounding or being hooked outwardly from the base of thetongue I 25 at the lower extremities of the sides |26 which round outwardly from the depressed portion |2'|.

The extension or. stranded cable I|5 constitutes a tail extension which, when the spring 93 is retracted, extends down below the lower end of the fuse casing I0 and ferrule I6 so that it may be gripped conveniently for setting the lfuse and placing the spring 93, under tension. With the spring 93 retracted, the setting of the fuse is accomplished by grasping the downwardly ex` tending tail extension H5 and pulling the same downwardly against the tension of the spring 93 until the conical bushing |20 is positioned below or clear of the bottom of the clip |22. The cable I I5 above the bushing |20 is then passed through the open side of the clip 22. Then, upon releasing the tail extension H5, the spring 93 draws the bushing up rmly against the conical socket |24 in the clip |22, and this cooperation of the bushing |20 with the hooked sides of the clip Aholds thespring 93 extended and the fuse in set position. A circuit is thusY established from the ferrule 14, upper cable terminal' and spring fastener 90, stranded conductor 95, lower cable terminal andspring fastener 96, upper fuse terminal |00, fuse link and strain wire assembly H0 and |02, lower fuse terminal |0|, stranded conductor H5, bushing |20 and clip |22 to the lower ferrule 'I6 through the tongue |25. The tail extension I5 below the conical bushing |20 may be out off or otherwise removed after the fuse is set, as above described, but it is to be understood that this removal of a part or all of the tail extension for setting the fuse or anchoringthe lowering end of the fuse element assembly to the lower ferrule on the fuse casing is not necessary within the scope of the present invention.

'I'he fuse shown and described is a spring type expulsion fuse. A surrounding sectionalized cork (not shown) andA an outer enclosing tube of water-proof paper, gummed paper or the like,

may be placed around the insulating tube H2 asin my copending application above identied, and this tube and the fuse element assembly per se may be 'modiiied in accordance with my said c'opending application. In the case of an ordinary air-type expulsion fuse as disclosed in my drop out type ejector cutout box of my copendr,ring application Serial No. 734,262, led July 9,

1934, the spring and cable assembly 93, 95 and the associated terminals and 496 may be removed by unscrewing the upper fuse terminal |00 from the tapped or threaded socket in the lower end of the terminal 96. Then, by merely threading the upper end of the upper fuse terminal into a button |35 of suitable conducting material and flanged radially as shown in Figure 14, the same fuse link assembly is adapted for use with the ordinary air type expulsion fuse or with the drop out type ejector cutout box of my copending application above identified. This makes the fuse link assemblyuniversal in that it is adapted for different types of devices.

It will be noted from an inspection of Figures l1 and 12 that the upper and lower sides of the convolutions of the spring 93 are flattened at |36. This ilattening increases the areas of contact 'of the convolutions of the spring with each other when the spring is retracted. A spring thus constructed in a device of this character will withstand high pressures without deformation or spring distortion. Lateral distortion and the tendency ofthe convolutions to roll upon one another, when in contact particularly, are avoided.

Itis to be further notedv that the stranded conductor 95 is wound into a helix in a direction counter to the lay of the strands of the conductor and placed within a spring 93 wound into a helix in the direction of the lay of the strands of the conductor, or counter to the winding of the conductor. In the illustrated embodiment cf the invention, a stranded conductor 95 with a lefthand lay is wound into a right-hand helix and placed within a spring 93 wound into a left-hand helix. This combination, particularly in a device of this sort, prevents the strands of the cable or the turns of the cable helix from paralleling the turns of the spring, and this greatly reduces the tendency for the cable to be pinched between the turns of the spring, which spring collapses to establish the desired gap upon blowing of the fuse.

'I'he cylinder or tube H2, which encloses the fuse element H0 and strain wire |02, in addition Y to confining the arc in a very small space and preventing charring and metal spattering on the tube liner '|2, and with its closed end attached to the movable terminal to prevent too free access of atmosphere to the fusible link and maintain the closure upon fusing of the link and movement of the movable fuse terminal, serves, by its downward extension below the ferrule 16 to perform the additional function of giving a visual indication when the fuse has been blown. The upper end of the tube or cylinder H2 being secured to the upper fuse terminal |00 by crimping or shrinking into the groove H6, it will be apparent that this tube H2 will move upwardly with the upper fuse terminal |00 and lower cable terminal andv spring fastener 96 upon retraction of the spring 93. Consequently, the absence of the projection of the lower end of the tube I|2 down from the bottom |40 of the ferrule 16 gives a visual indication that the fuse has blown and the spring 93 retracted. However, the presence of the lower end of the tube |I2 beneath the bottom l|40 of the ferrule 1 6 indicates visually that the fuse has not blown and that the device is in operative relation. 'I'he lower end of the tube H2, the absence or presence of which gives this indication, is indicated at |42 in Figure 12.

The cutoutl of my invention is set in operative relation by assembling the fuse parts as shown in Figures 11 and 12, and then screwing the upper threaded end 65 of the upper ferrule 14 into the insert 62 in the handle 60 of the plug member, the flange 9| at the top of the upper cable terminal and spring fastener being clamped between the inner end of the ltapped opening in the insert 62 and the upper end of the ferrule 14. The plug 4 is then inserted into the socket 2 to the position in which the lower ferrule 16 is in engagement with the spring fingers of the lower contact clip 45, and the upper ferrule 14 is in engagement with the spring fingers of the upper contact clip 44 as illustrated in Figures 3 and 4.

For the purpose of locking the fuse plug in position within the socket, the upper ferrule 14 is provided with an annular groove |50, Figures 3, 11 and 13, and a plurality of circumferentially spaced vent openings |52 open radially through the wall of the ferrule 14 from the interior of the ferrule into the annular groove |50. A tube lock pressure band 54, which is preferably formed of spring tempered sheetphosphor bronze or other suitable material, is disposed in the groove |50 and wrapped about the portion of the ferrule 14, through which the openings 52 extend., normally to close these openings. The band |54 is of a length so that its free ends overlap an appreciable distance in the normal position of the band, as shown in Figure '1. A coiled lock springs |56, preferably of spring wire or other suitable material, constitutes `a garter spring, provided at its opposite ends with hooks |58. When theseA hooked ends |58 are engaged as shown in Figure 7, the spring |56 embraces the pressure band |54 and normally lies entirely within the groove |501 The bottom shoulder |60 of the groove^|50 is preferably chamferedor inclined at its outer edge at |62 parallel, or substantially parallel, with theinclination of the upper inclined wall 4| of the channel 48 formed by spinning or rolling the external annular bead in the upper contact clip 44. 'Ihe garter spring |56 is of a strength normally to hold the pressure band |54 in contracted .position over the outer ends of the openings |52 removal and insertion of the plug. It also avoids i any necessity for turning of the plug to lock it in place, and it presents no locking parts which are operative under normal conditions when there is no blowing of the fuse, or which aresubject to corrosion or possible freezing. The locking device is, however, operable at th'e instant required. Upon blowing of the fuse, the pressure generated in the tube 1| causes an outward flow of air and gases Vfrom the interior of the fuse tube through the ,openings |52. This outward flow of air and gases expands the `pressure band |54 outwardly and, with it, the garter spring |56 outwardly into the annular groove y40 in the contact clip.44, as illustrated in Figure 13. This engagement of. the spring |56 in the groove 40 and with the upper inclined wall 4| of the contact clip 44 locks the plug 4 against'blowing out or loosening by the vreaction to the explosive force upon blowing of the fuse, and it does it at the instant required, namely, at the instant of blowing of the fuse. The plug is thus locked securely and positively in place. The paralleling of the shoulder |62 with the wall 4| of the contact clip 44 causes any tendency toward outward movement of the plug member to act in compression upon the turns of the coiled spring |56 and not in shear, such as might result if the walls 4| were normal to the axis of the fuse.. At the same time the inclination of the walls 4| enables free entry of the spring into the locking groove upon expansion into engagement therewith.

After the fuse is blown and the outward flow of air and gases through the openings |52 isspent,

4the thin metal expansion band and spring |56 are returned to their normal position within the groove` |50, as shown in Figure 11, by the retractive eiort of the spring. In this manner, the locking device not only operates at the instant required. but is released instantly the outward flow of air and gases is spent so that there is no added resistance to free removal of the plug from the socket.

The arrangement shown in the drawings is simple, compact and inexpensive, and it releases the locking device instantly the ow of air and gases or the explosive force is spent.

To renew the fuse link or reload the device, the plug 4 is iirst withdrawn from the socket 2. The fuse tube is then removed from the handle 60 by unscrewing the threaded upper end of the ferrule 65 from the insert 62. The blown fuse link assembly is then removed by unscrewing the upper fuse terminal |00 from the cable terminal and spring fastener 96, whereupon a new fuse link assembly is applied Vby screwing the upper terminal thereof into the tapped opening in the terminal 96, and the fuse link, spring and cable assembly is inserted into the fuse tube through the upper end of the upper ferrule 14. The tail extension ||5 is then grasped and drawn downwardly against the tension of the spring 93 and the conical bushing |20 engaged in the clip |22, whereupon the excess tail extension below the bushing |20 may be cut off with a pair of pliers.

While I have shown and described my invention with reference to the particular details of construction of one embodiment, it is to be understood that the invention may appear in different forms and with numerous modifications and varideviceconnecting said co-ntacts, and means re- Y sponsive to the blowing of the fuse for locking said fuse to at least one of said contacts.

3L In combination, a pair of contacts, a f use device connecting said contacts, means responsive to the blowing of the fuse for locking said fuse to at least one of said contacts, and means for releasing said locking means when the fuse has blown. v

4. In combinati-on, a pair cf contacts, a fuse device connecting said contacts, and means operable by the pressure evolved umn blowing of the fuse fc-r locking said fuse to at least one of said contacts.

5. A device cf the class described comprising plug and socket members provided with cooperating contacts, the plug member provided with a fuse connected with said contacts, and a locking device for said plug member, said locking device being normally in released position with said plug in place in said socket and operable'only at the instant required.

6. A device of the class described comprising plug and socket members provided with cooperating contacts, the plug member provided with a fuse connected with said contacts, a locking de vice for said plug member, said locking device being normally in released position, and rendered operative upon blowing of the fuse.

7. A device of the class described comprising plug and socket members provided with cooperating contacts, the plug member provided with a fuse connected With said contacts, and a locking device for said plug member, said locking device being normally in released position with said plug in place in said socket and operable by the pressure evolved upon blowing of the fuse.

8. A device of the class described comprising plug and socket members provided with cooperating contacts, the plug `member provided with a fuse connected with said contacts, and a locking device for said plug member, said locking device being rendered operative upon blowing of the fuse and means for releasing said locking device when the fuse has blown.

9. A devicel of the class described comprising plug and socket members provided with cooperating contacts, the plug member provided with a fuse connected with said contacts, and a locking device normally in released position withsaid plug in place in said socket and operable by the pressure evolved upon blowing of the fuse to lockv the plug in the socket, said locking device comprising means for releasing said locking device when the explosive force is relieved.

10. A device of the class described comprising plug and socket members provided with cooperating contacts, the plug provided with a fuse connected with said contacts, said fuse havingV an enclosure, port means opening from said enclosure, and a locking device disposed adjacent said port means and expandible intolocking engagement with the socket member by the eX- plosive force through said port means upon blow-A ing of the fuse.

1l. A device of the class described comprising plug and socket members provided with cooperating contacts, the plug provided with a fuse connected with said contacts, said fuse having an enclosure, port means opening from said enclosure, and a locking device disposed adjacent said port means and expandible into locking engagement with the socket member by the outward flow of air and gases through saidport means upon blowing of the fuse, said locking device comprising spring means normally holding said locking device in released Aposition and releasing said looking device when the fuse has blown.

12. A device of the class described comprising plug and socket members provided .with cooperating contacts, the plug member provided with a fuse connected with said contacts, said fuse having an enclosure, port means opening from said enclosure, a" pressure band surrounding the ported portion of said enclosure, and a coiled garter spring surrounding said pressure band, said spring being normally retracted to released position and expandible into locking engagement with the socketV member by the expansion of the pressure vband by the pressure evolved upon blowing of the fuse.

13. A device of the class described comprising plug and socket members provided with cooperating contacts, the plug member provided with a fuse connected with said contacts, a groove in the socket member, a groove in the plug member, and locking means normally disposed in the groove in one of said members to permit free insertion and removal of the plug member and engageable in the groove in the other member upon blowing of the fuse to lock the plug member in place in the socket member.

14. A device of the class described comprising plug and socket members provided with cooperating contacts, the plug member provided with a fuse connected with said contacts, a groove in the socket member, a groove in the plug member, and locking means normally disposed in the groove in one of said members to permit free insertion and removal of the plug member and engageable in the groove in the other member by the explosive force upon blowing of the fuse to lock the plug member in place in the socket member,

' said locking means comprising a pressure band and an annular spring of coiled form normally retracted to released position and expandible to locking position.

15. A device of the class described compris-A ing plug and socket members, a contact in the socket member, said contact having an annular groove, the plug member provided with a fuse having an enclosing tube, a contact ferrule on the fuse tube adapted to engage the contact in the socket member, said contact ferrule having a groove therein, port means opening from the interior of the fuse tube into said last groove, a pressure band disposed in the groove in the contact ferrule, and a spring 'surrounding said pressure band and normally disposed in the groove in said contact ferrule, said band and spring being expanded by the pressure evolved upon blowling of the fuse to force said spring into engagement with the groove in the socket contact to lock the plug in place in said socket member.

16. A device of the class described comprising plug and socket members, a contact in the socket member, said contact having an annular groove, the plug member provided with a fuse having an enclosing tube, a contact ferrule on the fuse tube adapted to engage the contact in the socket member, said contact ferrule having a groove therein, port means opening from the interior of the fuse tube into said last groove, a pressure band disposed in the groove in the contact ferrule, and a spring surrounding said pressure band and normally disposed in the groove in said contact ierrule, said band and spring being expanded .by

to force said spring into engagement with the Vgroove in the socket contact to lock the plug in place in said socket member, said spring being of coiled form arranged annularly and having hooked ends in engagement.

17. A device of the class described comprising plug and socket members, a contact in the socket member, said contact having an annular groove, the plug member provided with a fuse having an enclosing tube, a contact ferrule on the fuse tube adapted to engage the contact in the socket member, said contact ferrule having a. groove therein, port means opening from the interior of the fuse tube into said last groove, a pressure band disposed in the groove in said contact ferrule, and a spring embracing said pressure band and normally disposed in the groove in the contact ferrule, said band and spring being expandible by the pressure evolved upon blowing of the fuse to force said spring into engagement with the groove in the socket-contact to lock the plug in place iny saidsocket, the grooves in the contact in the socket member and in the contact ferrule on the fuse tube having inclined surfaces disposed substantially parallel so that the turns of the spring act in compression in locking the plug member in the socket member.

18. In combination, a socket member, a plug member adapted to be inserted into and removed from said socket member. a groove in the socket member, a groovel in the plug member, and a spring normally conned in the groove in one of said members and expandible into the groove in the other member for locking the plug member in the socket member, and the grooves in the socket and plug members having inclined surfaces disposed substantially parallel so that the turns of the spring act in Acompression in locking the plug member in the socket member.

19. Inya fuse, a fuse sleeve, a ierrule on said sleeve, a'groove in said ferrule, port .means opening from the interior of the sleeve into said groove,

and a locking device disposed in said groove and expandible by iiow of air and gases through said port means upon blowing of the fuse.

20. In a fuse, a fuse sleeve, a ferrule on said.

sleeve a groove in said ferrule, port means opening from the interior of the sleeve into said groove,

a locking device disposed in said groove and expandible by the explosive force through said port means upon blowing of the fuse, said locking device comprising a pressure band disposed in said groove and surrounding the ported portion of said ferrule, and a spring surrounding said band and normally disposed in said groove.

21. A contact assembly comprising the combination of-a metal ring having a. bore, a groove in the bore, and a wrought metalcontact member having a tubular body fitting within the bore and having a hollow rib tting tightly in the groove and having integral contact lingers extending from one edge of said body.

22. 'I'he combination of claim 21 wherein the outer ends of said fingers have portions offset toward the axis of the 'said tubular body, and a garter spring embracing said offset. portions.

23. The combination of claim 21 with spring means for pressing the ends of the fingers toward the axis of the said tubular body, and a band encircling the fingers for limiting the travel of said fingers radially away from said axis.

24. The combination of 'claim 21 wherein the tubular body portion has an integral flared portion at the end opposite the ngers.

25. As an article of manufacture, a tubular wrought metal body portion having an integral ared portion forming an arc chute at one end and integral fingers separated by slots and extendingfrom the other end, said body portion and said fingers being of substantially uniform thickness. l

26. A contact clip of tubular form slotted at spaced points to form resilient contact fingers, a reinforcing spring surrounding said fingers and a reinforcing ring floating on said spring to limit its outward expansion, said contact'clip being open and unobstructed at each end.

27. A contact clip of tubular form having intermediate its ends, an external rib and a flare at one end ,forming an arc chute of generally trumpet form, the opposite end oi said clip having slots dening resilient contact ngers, said contact clip being open and unobstructed at each end.

28. A contact clip of tubular form having within its length an internal groove and an external rib and a are at one end forming an arc chute of generally trumpet form, the opposite end of said clip having slots defining resilient contact fingers, a reinforcing spring surrounding said fingers, and a reinforcing ring floating on said spring to limit its outward expansion, said contact clip being open -and unobstructed at each end.

29. A contact assembly comprising a contact base having a bore provided with Aa groove within its length, a contact clip of tubular form secured in the bore in said base by a projecting part of its wall conforming to the shape of the groove in the bore of the base, said contact clip being open and unobstructed at each end.

30. A contact assembly comprising a base having a bore provided with a groove within its length, a 4contact clip of tubular form securedin the bore in said base by a projecting part of its wall conforming to the shape of the groove in the bore of the base, said clip projecting from said base and being slotted at spaced points to form resilient contact -fingers, av reinforcing spring surrounding said ngers, and a reinforcing ring floating on said spring to limit its outward expansion, said contact clip being open and unobstructed at each end.

3l. A contact assembly comprising a contact base having a bore provided with a groove within its length, a contact clip of tubular form secured in the bore in said base by a projecting part of its wall conforming to the shape of the groove in the bore of the base, said clip projecting from said. base and being slotted at spaced points to form resilient contact fingers, a reinforcing spring surrounding said ngers and a reinforcing ring floating on said spring to limit its outward expansion, and the other projecting end of said clip being dared out to forman arc Achute of generally trumpet form, said contact clip being open and unobstructed at each end.

.32. In combination with a fuse tube having an open end, a ferrule on said end of the tube,

' a'fuse link in the tube lconnected to said ferrule, lblowing of said link causing the expulsion of lar housing member provided with a bore for rev ceiving the fuse tube and a counterbore at one end, a terminal ring seated in said counterbore and embracing and holding said body portion in alignment with the bore of the housing.

34. A tubular wrought metal terminal memi ber having spring fingers extending from one end, and a flared metallic arc chute forming an extension at the other end.

35. In combination a fuse tube, a ferrule embracing the fuse tube, the tube having a groove ofrectangular cross section on its outer surface.

-between its ends providing an axially facing shoulder opposed to said first shoulder anda thin conical split spring ring having its larger end expanded into and lying wholly within the groove in the ferrule and having its smaller end lying wholly within the groove in the cylindrical body whereby said ring forms an annular diagonal strut between said oppositely facing shouldders.

37. In combination, a metal ferrule having a cylindrical bore, a member of insulation having a portion provided with an external cylindrical surface, said member and said ferrule being telescopically tted together, and a thin split spring ring of substantially uniform thickness which when permitted to expand radially assumes the form of a frustum of a hollow cone having a radial projection substantially in excess of its actual thickness, said cylindrical portion having an external groove wide enough to receive said -ring and of a depth substantially equal to the thickness of said ring and providing an axially facing shoulder to be engaged by the small dlameter end of said ring when it assumes its conical form, said ferrule having an internal groove deep enough to receive the large diameter end of the ring when it assumes its conical form, said internal groove providing an axially facing shoulder which is adapted to engage the end face of the large diameter end of the ring when it is in conical form, said ring being disposed in expanded conical form in said grooves and forming anannular diagonal strut betweenv the said shoulder on the ferrule and the said shoulder on the said portion of the member.

38. In a device of the class described, the combination of a tubular casing, a movable system within said casing including a movable terminal member and a coil spring normally under tension and connected to said terminal member, said spring having the sides of its convolutions attened to withstand high pressure of the convolutions against each other without displacement edgewise relative to each other.

39. In a cutout, a plug member and a cooperating socket member, said socket member comprising a sleeve of insulation having contacts therein, said plug member comprising an expulsion fuse having a fuse sleeve provided with terminal contacts adapted to engage with the contacts in the socket member, a movable system within said fuse. sleeve including a terminal member and a ilattened spring wire coiled helically and connected to said terminal member.

40. In a device of the class described, a movable system including a movable terminal member, a stranded cable connected to said terminal member and wound into a helix lcounter to the lay of the strands of the cable, and a coiled spring normally under tension and connected to said terminal member, said coiled spring being wound into a helix counter toA the winding of the helix in said strand'whereby the strands of the cable andthe turns of the cable helix are prevented from paralleling theturns of the spring to reduce the tendency for the cable to be pinched between the turns of the spring.

41. In a device of the class described, a movable system including a movable terminal member, a stranded cable connected to said terminal member and wound into a helix, and a coiled spring normally under tension and connected to said terminal member, said coiled spring being wound into a helix counter to the winding of the helix in said strand whereby the turns of the cable are prevented from paralleling the turns of the spring to reduce the tendency for the cable to be pinched between the turns of the spring.

42. In combination, a tubular casing, a ferrule thereon, a plunger, a fusible element between the plunger andsaid ferrule, and a spring attached to said plunger and having its convolutions flattened to withstand high pressure of the convolutions against each other without displacement edgewise relative to each other.

43. In combination in `a fuse device, an expulsion fuse having a ferrule through which arc gases are adapted to 'be expelled, a stationary terminal member providing a ring having an internal groove, a contact clip of tubular stock having slotted fingers engaging said ferrule, and having a cylindrical portion provided with a hollow annular ilange tting into the groove in said ring, and having a flared integral portion extending beyond the opening in the ferrule to form an arc chute.

44. In combination in a fuse device, an expulsion fuse having a ferrule through which arc gases are adapted to be expelled, a cooperating contact; clip of tubular stock having 4slotted ngers engaging said ferrule, and having a flared integral arc chute portion extending beyond the opening in the ferrule. l

45. In combination in a fuse device, a stationary tubular mounting, an expulsion fuse having a ferrule at one end, a stationary terminal member mounted at one end of the mounting, said terminal member being provided with a ringlike portion having an internal peripheral groove,

a contact clip of tubular stock having slotted lar housing having a bore, an expulsion fuseadapted to be mounted in the bore of the tubular housing, a counterbore being formed at one end of the bore to provide a terminal receiving recess, a terminal having a ringlike portion mounted in said recess, said ringlike portion being Asubstantially coaxial with the bore of the housing, said ringlike portion having a groove on its inner periphery, a contact clip of tubular stock provided with a hollow annular ilange' tting into said groove to form an electrical and mechanical connection with the terminal, said clip having integral fingers extending inwardly of the bore of the housing, a constricting spring embracing the fingers and a non-expansible ring disposed in the housing and backing up said spring.

47. In combination, a pair of supporting contacts, an expulsion type fuse removably mounted in said contacts, and pneumatic means actuated by blowing of the fuse for locking the fuse to one of the supporting contacts during blowing of the fuse only to prevent the fuse from shifting in the contacts on blowing or the fuse..

48. In combination a mounting for a. inse, a

fuse supported in said mounting and being normally tree to be inserted into or withdrawn from the mounting, said fuse when blown by excess vcurrent tending to shift in said mounting, and

pneumaticaily operated locking means actuated by blowing of the fuse to lock the fuse to the mounting during blowing of the fuse. 

